In order to prevent or minimize the occurrence of fire
accidents, the basic knowledge of fire should be known. Fires can be classified
into five main categories based on the type of materials that initiates the
start of fire. (I) Class A fires
usually used to classify the type of fire in ordinary combustible materials
(wood, cloth, paper, rubber and plastics). (II)
Fire in flammable liquids, gases, oil, and paint are classified as Class B fires. (III) Class C fires involves energized
electrical equipment non-conductivity of the extinguishing agent. And (IV) Class D fires are the fires that occur
in the combustible metals, such as magnesium, titanium, zirconium, sodium and
etc. (V) Class K fires are the most
dangerous fire as it deals with cooking oils and greases.
For Class A fires, it is often occur in food storage rooms,
dining areas, restrooms, and refuse storage areas. Some of the fire scenarios
that can be classified as Class A fires are such as fire started in a trash can
which ignited by a cigarette butt or a
plastic container that comes in contact with a range burner. This class of fire
can be easily put out by water based (water and foam or water mist) or a dry
chemical based fire extinguisher. Water and foam or water mist extinguishers
extinguish the fire by removing the heat element. As for the dry chemical, it
interrupts he chemical reaction of the fire triangle.
For Class B fires, the fire often occurs in the maintenance
areas. As an example, aerosol cans exploding due to the storing location very
near to a heat source. This type of fire can be put out by carbon dioxide based
and dry chemical based fire extinguisher.
Class C fires related to electrical equipment, for instance,
when frayed cord comes in contact with water while the machine is still
operating, or overheating of a toaster that caught a fire. Fire extinguishers
with non-conductive materials can be used to extinguish the fire such as carbon
dioxide based fire extinguishers.
As for Class D fires in which combustible metals are
involved, only dry powder extinguishers can be used. These extinguishers are
similar to dry chemical except that they extinguish the fire by separating the
fuel from the oxygen element or by removing the heat element of the fire
triangle. However, they are ineffective on all other classes of fires.
Lastly, Class K fires which often occurs in kitchen; flames
from a grill igniting grease deposits on a hood filter or leaving a frying pan
unattended on the stove. Grease fire can get out of control quickly and spread
from the stove throughout the kitchen into other rooms of the house. Grease
fire can caused serious injury and extensive property damage. Wet chemical of
Class K extinguishers were developed specifically for the modern, high
efficiency deep fat fryers in commercial cooking operations. The wet chemical
extinguishes fire by removing the heat of the fire triangle and prevents the re-ignition
by creating a barrier between the oxygen and fuel elements.
The sources at which the fire first started are very
important as it helps to identify the classification of fires. After knowing
the main source that causes the fire, it is important to use the correct types
of fire extinguisher to put out the fire, as materials in the extinguishers
used will either put out the fire or reacts vigorously with fire causing large
flames and smoke.